An early 19th-century physiologic Georg Muller suggested that the nature of sensory experience was determined by the sensory nerves; this was called the Doctrine of Specific Nerve Energies. Muller suggested that auditory sensations such as the pitch and loudness of sounds were experienced because of the specific energy of the auditory nerve, and that no matter how this nerve was stimulated, the result would be the experience of a sound with a pitch and loudness. He then suggested a thought experiment: what would happen if one were able to attach the auditory nerves to the eyes, and the optic nerves to the ears?